The dietary effect of different wheat cultivars for broiler chickens

Barley, an Undervalued Cereal for Poultry Diets: Limitations and Opportunities

Simple Summary

With the ever-increasing demand for poultry products, the continuous supply of conventional cereal grains such as maize has become a challenge. Barley has been recognised as a potential alternative feed ingredient that can replace common cereal grains in poultry diets. However, due to several limitations such as the presence of various anti-nutritive factors and the variability in nutrient composition and quality, the use of barley in poultry diets remains comparatively low. The previous findings on the optimum use of barley in poultry diets are also inconsistent primarily due to differences in research methodologies. The importance of using accurate nutrient profiles for specific barley cultivars to formulate barley-based diets is emphasised in this review. Moreover, the need to adapt feed processing conditions suitable to different barley cultivars to increase the inclusion of barley in poultry diets is highlighted in this review.

Abstract

The supply of conventional cereal grains, especially of maize, will be a significant constraint to the future growth of the poultry industry. Various alternative feed ingredients are being tested to replace maize in poultry diets. Barley (Hordeum vulgare L.) is one such feed ingredient, the use of which remains limited in poultry diets due to its low metabolisable energy, presence of anti-nutritive, soluble non-starch polysaccharides and consequent inter-cultivar variability. Differences in research methodologies used in published studies have also contributed to the inconsistent findings, preventing a good understanding of the nutritional value of barley for poultry. The importance of using accurate nutrient profiles, specifically metabolisable energy and digestible amino acids, for specific barley cultivars to formulate barley-based diets is emphasised. Nutritionists should also pay close attention to feed processing conditions tailored to the specific barley cultivars to increase the barley inclusion in poultry diets.

Antioxidant Status, Blood Constituents and Immune Response of Broiler Chickens Fed Two Types of Diets with or without Different Concentrations of Active Yeast

Simple Summary

Rations for broilers can be safely supplemented with probiotics such as active Saccharomyces cerevisiae (SC) yeast to stimulate oxidative reactions and immune response against stress and infectious agents. The current study suggested that SC yeast enhanced antioxidant capacity, growth rate, immune organ weights, immune response and the survival rate of broilers after Avian Influenza virus challenge at 38 days of age.

Abstract

Probiotics, such as active yeasts, are widely used to enhance poultry production and reduce feeding costs. This study aimed to investigate the antioxidant and immune responses of broilers to different concentrations of active Saccharomyces cerevisiae (SC) when supplemented to two types of diets. A total of 216 1-day-old Arbor Acres unsexed chicks were used in a factorial design, involving two feeds (regular- versus low-density diet) and three concentrations of SC (0%, 0.02% and 0.04%). The results revealed that the low-density diet reduced the body weight and production index of broilers. The addition of SC improved the production index more than the control diet. Total antioxidant capacity (TAC), alanine aminotransferase (ALT), aspartate aminotransferase (AST) and eosinophils were significantly higher in response to the regular-density diet than the low-density diet; however, phagocytic activity (PA), lymphocyte and lysozyme activity (LYS) were lower. Saccharomyces cerevisiae reduced ALT, AST, malondialdehyde (MAD) and TAC more than the standard set, but improved packed cell volume (PCV), hemoglobin (Hgb), red blood cells (RBCs), lymphocytes, monocytes, heterophils, phagocytic index (PI) and the immune response to Newcastle disease virus (NDV) and avian influenza (AI). In conclusion, supplementation of a regular- or low-density diet with SC at a concentration of 0.02% or 0.04% improved the antioxidant parameters, immune status and production index of broilers against stress and infectious agents.

The Potential of Locally-Sourced European Protein Sources for Organic Monogastric Production: A Review of Forage Crop Extracts, Seaweed, Starfish, Mussel, and Insects

Organic monogastric agriculture is challenged because of a limited availability of regional and organic protein-rich ingredients to fulfill the amino acid requirements. The development of novel feed ingredients is therefore essential. The use of starfish (Asterias rubens), mussel (Mytilus edilus), insect, green and brown seaweed, and forage crop extracts exhibits different approaches to increase protein availability in a sustainable manner through improving the protein quality of existing ingredients, better use of under- or unutilized material, or development of circular bioeconomy. This review assessed limitations and opportunities of producing, processing, and using these novel ingredients in feed. The use of non-renewable resources and the effect on the environment of production and processing the feed ingredients are described. Protein concentration and amino acid quality of the feed ingredients are evaluated to understand their substitution potential compared with protein-rich soya bean and fishmeal. Feedstuffs’ effect on digestibility and animal performance is summarized. With the exception of seaweed, all novel ingredients show potential to partly substitute fishmeal or soya bean fulfilling part of the protein requirement in organic monogastric production. However, improvements during production and processing can be made to enhance protein quality, sustainability of the novel ingredients, and nutrient utilization of novel feed ingredients.

Nutrient Content of Different Wheat and Maize Varieties and Their Impact on Metabolizable Energy Content and Nitrogen Utilization by Broilers

Simple Summary

The current standard for the determination of the energy value of feed is to use regression equations; however, these equations are imprecise and may affect the correct estimation of energy for several reasons. First of all, these equations include the values of some raw components, such as crude protein, ether extracts, and N-free extracts, but not different forms of fiber, which in high concentration reduces the energy value of poultry feed. In addition, in the tables, there are average values for different feeds, which do not take into account differences between varieties of the same species, which, at least in case of grains may be much larger than differences between two different species. Another important aspect is that the concentration of various components, including antinutritional factors, affects their mutual use and thus the energy value of feed. This work was aimed at improving the precision of estimating the energy value of poultry feed by incorporating detergent and dietary fiber as well as additional nutrients such as starch and total sugars separately. In addition, the authors suggest considering the values characteristic of selected grain in the energy calculations rather than the mean values for the species, because it may improve the precision of the result.

Abstract

The study aimed to determine the effect of nutrients of wheat (nine cultivars) and maize (nine cultivars) grain on nitrogen balance and apparent metabolizable energy (AME_N) content for broiler chickens. In vivo digestibility and balance trials were carried out with 90 Ross 308 chickens (2 × 9 groups with 5 birds per group) aged from 42 to 49 days, separately for each cultivar. Considerable variation within each cereal species in fiber and non-fiber carbohydrate fractions and nutrient digestibility of grain were demonstrated. Additionally, regression equations were proposed which allow the estimation of AME_N content of wheat and maize grain varieties based on simple analytical procedures, including cell wall components, starch, and sugars. For practical purposes, these equations seem to be the best solution while reducing time, labor, and cost of analytical procedures.

Effect of Different Levels of Multienzymes on Immune Response, Blood Hematology and Biochemistry, Antioxidants Status and Organs Histology of Broiler Chicks Fed Standard and Low-Density Diets

This study was executed to investigate the effect of supplementing three multienzyme levels (0, 0. 1, and 0.2%) with two types of diet [standard diet (SD) vs. low-density diet (LDD)] on immune response, blood hematology and biochemistry, antioxidant status, and organ histology of broilers during 1–38 days of age. A total of 216 unsexed 1-day-old Arbor Acres broiler chicks were randomly distributed, on a factorial design (2 × 3), to six treatments each with six replicates. There were six chicks per replicate. Results showed that LDD significantly decreased body weight gain (BWG) of broilers, but did not affect the European Production Efficiency Index (EPEI). Addition of multienzymes at both levels (0.1 and 0.2%) significantly increased BWG and improved EPEI, compared to the control diet. Alanine aminotransferase (ALT), aspirate aminotransferase (AST), malondialdehyde (MDA), lymphocyte, lymphocyte transformation test (LTT), and phagocyte activity (PA) were significantly higher for LDD than the SD, but eosinophil was lower. Supplementation of multienzymes significantly decreased ALT, AST, and MDA, compared to the control group, but increased packed cell volume (PCV), hemoglobin (Hgb), lymphocytes, and monocytes. Immune organs, such as spleen, thymus, and the bursa of Fabricius were significantly increased with multienzyme supplementation. It could be concluded that multienzyme supplementation at either 0.1 or 0.2% to SD or LDD improved EPEI and immune status of broiler chicks.

Wheat sample affects growth performance and the apparent metabolisable energy value for broiler chickens

1. The aim of this study was to examine chemical composition, quality characteristics, apparent metabolisable energy (AME) and nutrient utilisation of wheat samples currently available to the UK poultry industry and their effect on broiler growth performance. 2. Seventeen current UK wheat samples were used to formulate 17 diets, all of which included 670 g/kg of each wheat sample and 330 g/kg of a balancer feed. Eight hundred 1-day-old male Ross 308 broilers were allocated randomly to 160 raised floor pens. Each diet was replicated eight times, fed ad libitum from 0 to 21d age in a randomised complete block design. Excreta were quantitatively collected during the last 3 days for AME determination. 3. The content of protein, ash and gross energy (GE) ranged from 97 to 143 g/kg DM, 12.8 to 19.6 g/kg DM and 17.81 to 18.24 MJ/kg DM, respectively. The amount of starch and total non-starch polysaccharides (NSP) ranged from 671 to 728 and 80.1 to 98.2 g/kg DM, respectively. The quality characteristics of wheat samples were in the expected range. 4. There were differences (P < 0.05) in AME and N-corrected AME (AMEn) of wheat samples. The AME of the wheat had a maximum range of 1.13 MJ/kg DM between samples. Dry matter retention (DMR) and fat digestibility (FD) were significantly different (P < 0.05) between wheat samples. 5. The daily feed intake (FI) and weight gain (WG) of broilers fed two wheat samples were significantly (P < 0.05) lower as compared to other samples and their low FI and WG were not related to their chemical composition and quality characteristics. 6. The ash content of wheat samples was negatively associated with AMEn (r = - 0.489, P < 0.05). The coefficient of FD was positively related to AMEn (r = 0.552, P < 0.05). 7. Chemical composition and quality characteristics of the wheat did not relate (P > 0.05) to FI and WG of broilers. There was no relationship between growth performance of broilers and AMEn of the wheat samples.

Assessing the effect of ingredients variability on the composition of the final complete feed for swine

To characterize the variability of 11 feed ingredients and their impact on the final feed, 728 ingredient samples were collected during 5 months in a feed-plant and were analyzed by near-infrared spectrophotometry (NIRS). Six diets for fattening pigs and gestating sows were formulated using regional information of ingredient chemical composition (reference): LIM, limited; EU, common European; and MULT, multi-ingredient; respectively, including 5, 7, and 10 ingredients. The formulas were replicated 15 times using actual chemical composition (NIRS) from three samples per ingredient and month. This theoretical procedure was validated through small-scale manufacturing 30 LIM-diets, which samples were proximal (PA) and NIRS analyzed for dry matter and crude protein (CP) contents. Those mixtures were also PA analyzed. The ingredients showed coefficient of variation (CV %) higher for crude fiber (CF) (2.6%–18.3%) than CP (2.0%–9.3%). Comparing all diets for all chemical components, variability was reduced when including more ingredients from 0.5%–5.5% to 0.3%–2.6% CV. In most cases, the actual chemical composition of the diets underestimated their reference formula (1.3%–10.8%, CP and CF). A deviation from the targeted diet occurs if variability is not regarded. Therefore, a proper method to predict ingredient composition and nutritional value before use may increase the accuracy of diet formulation between 2% and 10%.

Combined effect of using near-infrared spectroscopy for nutritional evaluation of feed ingredients and non-starch polysaccharide carbohydrase complex on performance of broiler chickens

This study was carried out to evaluate the combined effect of using near-infrared spectroscopy (NIRS) for nutritional evaluation of feed ingredients and the addition of non-starch polysaccharide carbohydrase complex (NSP enzymes) on the growth performance of broilers fed diets produced with low-quality wheat and soybean meal. A 2 × 2 trial design was performed, with seven replicates of 40 male Ross 308 broilers per treatment, evaluating the effect of the addition of NSP enzymes and the ingredients' nutritional matrix based on table values or NIRS values. Diets without added enzymes were formulated to reach nutritional requirements, whereas diets with enzymes were reformulated, reducing the apparent metabolizable energy (AME) by 85 kcal/kg. In the overall period (days 0-35), broilers fed diets formulated using NIRS values had higher (P < 0.001) average daily gain (+11.3%) and daily feed intake (+7.2%), and a lower (P < 0.001) feed conversion ratio (-5.3%) compared to those fed diets formulated using table values. When formulating diets for broilers with low-quality feed ingredients, performance can be improved by considering NIRS values and by the addition of NSP enzymes, even with a reduction of AME. These nutritional approaches are efficient in improving broilers' performances by themselves and even more so when they are combined.

Determination of ileal digestible and apparent metabolizable energy contents of expeller-extracted and solvent-extracted canola meals for broiler chickens by the regression method

The present study was conducted to determine ileal digestible energy (IDE), metabolizable energy (ME), and nitrogen-corrected ME (MEn) contents of expeller- (EECM) and solvent-extracted canola meal (SECM) for broiler chickens using the regression method. Dietary treatments consisted of a corn-soybean meal reference diet and four assay diets prepared by supplementing the reference diet with each of canola meals (EECM or SECM) at 100 or 200 g/kg, respectively, to partly replace the energy yielding sources in the reference diet. Birds received a standard starter diet from day 0 to 14 and the assay diets from day 14 to 21. On day 14, a total of 240 birds were grouped into eight blocks by body weight and randomly allocated to five dietary treatments in each block with six birds per cage in a randomized complete block design. Excreta samples were collected from day 18 to 20 and ileal digesta were collected on day 21. The IDE, ME, and MEn (kcal/kg DM) of EECM or SECM were derived from the regression of EECM- or SECM-associated IDE, ME and MEn intake (Y, kcal) against the intake of EECM or SECM (X, kg DM), respectively. Regression equations of IDE, ME and MEn for the EECM-substituted diet were Y = -21.2 + 3035X (r(2) = 0.946), Y = -1.0 + 2807X (r(2) = 0.884) and Y = -2.0 + 2679X (r(2) = 0.902), respectively. The respective equations for the SECM diet were Y = 20.7 + 2881X (r(2) = 0.962), Y = 27.2 + 2077X (r(2) = 0.875) and Y = 24.7 + 2013X (r(2) = 0.901). The slope for IDE did not differ between the EECM and SECM whereas the slopes for ME and MEn were greater (P < 0.05) for the EECM than for the SECM. These results indicate that the EECM might be a superior energy source for broiler chickens compared with the SECM when both canola meals are used to reduce the cost of feeding.

Effects of Post-harvest Storage Duration and Variety on Nutrient Digestibility and Energy Content Wheat in Finishing Pigs

This study was conducted to investigate the effects of post-harvest storage duration and wheat variety on the digestibility and energy content of new season wheat fed to finishing pigs. Two wheat varieties (Shi and Zhong) were harvested in 2013 and stored in the warehouse of the Fengning Pig Experimental Base at China Agricultural University for 3, 6, 9, or 12 mo. For each storage period, 12 barrows were placed in metabolism crates and allotted to diets containing 1 of the 2 wheat varieties in a randomized complete block design. The experimental diets contained 97.34% wheat and 2.66% of a vitamin and trace mineral premix. With an extension of storage duration from 3 mo to 12 mo, the gross energy (GE) and crude protein (CP) of the wheat decreased by 2.0% and 12.01%, respectively, while the concentration of neutral detergent fiber (NDF), acid detergent fiber (ADF) and starch content increased by 30.26%, 19.08%, and 2.46%, respectively. Total non-starch polysaccharide, total arabinose, total xylose and total mannose contents decreased by 46.27%, 45.80%, 41.71%, and 75.66%, respectively. However, there were no significant differences in the chemical composition between the two wheat varieties with the exception of ADF which was approximately 13.37% lower in Shi. With an extension of storage duration from 3 mo to 12 mo, the digestible energy (DE), metabolizable energy (ME) content and the apparent total tract digestibility of GE, CP, dry matter, organic matter, ether extract, ADF and metabolizability of energy in wheat decreased linearly (p<0.01) by 5.74%, 7.60%, 3.75%, 3.88%, 3.50%, 2.47%, 26.22%, 27.62%, and 3.94%, respectively. But the digestibility of NDF changed quadratically (p<0.01). There was an interaction between wheat variety and storage time for CP digestibility (p<0.05), such that the CP digestibility of variety Zhong was stable during 9 mo of storage, while the CP digestibility of variety Shi decreased (p<0.05). In conclusion, the GE, DE, and ME of wheat was stable during the first 3 to 6 mo of post-harvest storage, and decreased during the following 6 to 12 mo of storage under the conditions of this study.

Relationship between wheat characteristics and nutrient digestibility in broilers: comparison between total collection and marker (titanium dioxide) technique

Three wheat cultivars (Orpheus, Rustic, and Viscount) were used to formulate 3 test feeds (62.4% wheat) in a broiler digestibility trial. The diets were fed to male Ross 308 broiler chickens. The wheat cultivars mainly differed in their amount of non-starch polysaccharides ( NSP: ). The cultivar Orpheus was chosen to represent a high amount of NSP (102 g/kg DM), whereas the cultivars Rustic and Viscount represented low amounts of NSP (83.4 g/kg DM and 73.9 g/kg DM, respectively). Furthermore, the cultivars Orpheus and Viscount were feed quality wheat, whereas Rustic was a milling quality wheat. Nutrient digestibilities and AMEn contents of the diets were measured from 18 to 22-days-old by total excreta collection, or with the use of the indigestible marker titanium dioxide. In addition, the ileal viscosity was measured when the broilers were 25-days-old. Wheat cultivar affected N retention, DM digestibility, and AMEn. In general, the feed formulated with the high NSP wheat cultivar Orpheus resulted in the least favorable nutrient digestibilities and AMEn, whereas the results were better when the feed was formulated with the low NSP cultivars Viscount and Rustic. Feeding the Rustic cultivar caused the highest intestinal viscosity, although this was not reflected in the animal responses. Nutrient digestibilities and AMEn content of the diets were lower when calculated with the titanium dioxide marker than with the total excreta collection procedure. Moreover, the P-values of the effect of wheat cultivar on DM digestibility, N retention, crude fat digestibility and AMEn were lower with the use of the titanium dioxide marker. It can be concluded that wheat cultivar affected nutrient digestibility and AMEn, and that the observed differences were related to the amount of NSP. Furthermore, both the titanium dioxide marker and the total excreta collection methods showed the same trends despite the different values obtained. The titanium dioxide marker method was the simplest to use and produced valid results.

Energy utilization and growth performance of chickens fed novel wheat inbred lines selected for different pentosan levels with and without xylanase supplementation

Different F5 recombinant inbred lines from the cross Yumai 34×Ukrainka were grown in replicated trials on a single site in one harvest year at Rothamsted Research. A total of 10 samples from those lines were harvested and used in a broiler experiment. Twenty nutritionally complete meal-form diets that had 630 g/kg of wheat with different amounts of pentosan, with and without exogenous xylanase supplementation, were used to compare broiler growth performance and determine apparent metabolizable energy corrected for N retention (AMEn). We examined the relationship between the nutritive value of the wheat samples and their chemical compositions and results of quality tests. The amounts of total and water soluble pentosans in wheat samples ranged from 36.7 to 48.0 g/kg DM, and 6.7 to 11.6 g/kg DM, respectively. The mean crude oil and protein contents of the wheat samples were 10.5 and 143.9 g/kg DM, respectively. The average determined value for the kinematic viscosity was 0.0018 mPa.s, and 2.1 mPa.s for the dynamic viscosity. The AMEn of the wheat-based diets had a maximum range of 0.47 MJ/kg DM within the ten wheat samples that were tested. Xylanase supplementation improved (P<0.05) dietary AMEn, dry matter, and fat digestibility coefficients. There was a positive (P<0.05) relationship between in vitro kinematic viscosity of the wheat samples and the total pentosan content. There was a negative relationship between the total pentosan content in the wheat and broiler growth performance. An increase by 10 g of pentosan per kg of wheat reduced (P<0.001) daily feed intake and weight gain by 2.9 g and 3.5 g, respectively. The study shows that the feeding quality of wheat samples can be predicted by their total pentosan content. Supplementary xylanase improved energy and nutrient availability of all wheat samples that was independent of differences in pentosan content.

The effect of variety and growing conditions on the chemical composition and nutritive value of wheat for broilers

The aim of this study was to examine the effect of variety and growing conditions of wheat on broiler performance and nutrient digestibility. One hundred and sixty-four wheat samples, collected from a wide range of different sources, locations, varieties and years, were analyzed for a range of chemical and physical parameters. Chemical and physical parameters measured included specific weight, thousand grain weight (TG), in vitro viscosity, gross energy, N, NDF, starch, total and soluble non-starch polysaccharides (NSP), lysine, threonine, amylose, hardness, rate of starch digestion and protein profiles. Ninety-four of the wheat samples were selected for inclusion in four bird trials. Birds were housed in individual wire metabolizm cages from 7 to 28 d and offered water and feed ad libitum. Dry matter intake (DMI), live weight gain (LWG) and gain:feed were determined weekly. A balance collection was carried out from 14 to 21 d for determination of apparent metabolizable energy (AME), ME:gain, DM retention, oil and NDF digestibility. At 28 d the birds were sacrificed, the contents of the jejunum removed for determination of in vivo viscosity and the contents of the ileum removed for determination of ileal DM, starch and protein digestibility. The wheat samples used in the study had wide-ranging chemical and physical parameters, leading to bird DMI, LWG, gain:feed, ME:GE, AME content and ileal starch and protein digestibility being significantly (p<0.05) affected by wheat sample. A high level of N fertilizer application to the English and NI wheat samples tended to benefit bird performance, with increases of up to 3.4, 7.2 and 3.8% in DMI, LWG and gain:feed, respectively. Fungicide application also appeared to have a positive effect on bird performance, with fungicide treated (+F) wheat increasing bird DMI, LWG and gain:feed by 6.6, 9.3 and 2.7%, over the non-fungicide treated (-F) wheats. An increase (p<0.1) of 9.3% in gain:feed was also observed at the low seed rate of 40 compared to 640 seeds/m². It was concluded that the type of wheat sample and environmental growing conditions significantly affects bird performance when fed wheat-based diets.

Chemical and physical predictors of the nutritive value of wheat in broiler diets

The aim of this study was to establish relationships between chemical and physical parameters of wheat with performance and digestibilities of feed components in broiler chickens fed on wheat-based diets. Ninety-four wheat samples were selected for inclusion in four bird trials. Birds were housed in individual wire metabolism cages from 7 to 28 d and offered water and feed ad libitum. Dry matter intake (DMI), liveweight gain (LWG) and gain:feed were measured weekly. A balance collection was carried out from 14 to 21 d for determination of apparent metabolizable energy (AME), ME:gain, dry matter retention, oil and neutral detergent fibre (NDF) digestibility. At 28 d the birds were humanely killed, the contents of the jejunum removed for determination of in vivo viscosity and the contents of the ileum removed for determination of ileal dry matter, starch and protein digestibility. When wheat parameters were correlated with bird performance data, it was found that specific weight was not significantly (p>0.05) related to bird performance. Bird DMI, LWG and gain:feed were best correlated (p<0.05) with the rate of starch digestion, although the coefficients of correlation (r) were still low (0.246 to 0.523). A negative relationship (p<0.01) between AME and total (r = −0.432) and soluble (r = −0.304) non starch polysaccharide (NSP) was observed in this study. Thousand grain weight (TG) was positively correlated with DMI (r = 0.299), LWG (r = 0.343) and gain:feed (r = 0.371). When establishing multiple regression relationships, correlation coefficients greater than 0.8 were achieved for DMI, LWG, gain:feed and ileal crude protein digestibility. However, the economics involved in determining the parameters involved in the regressions make the process impractical.

Fiber and nonstarch polysaccharide content and variation in common crops used in broiler diets

The current paper reviews content and variation in fiber and nonstarch polysaccharides (NSP) of common crops used in broiler diets. The cereal grain is a complex structure, and its cell walls (CW) differ in their composition and hence properties. Arabinoxylan (AX), mixed linkage (1→3; 1→4)-β-glucan (β-glucan), cellulose, and the noncarbohydrate component lignin are the predominant polymers in cereals. They occur in different proportions depending on the species and tissue type. Rye, triticale, wheat, corn, and sorghum are all rich in AX, whereas barley and oats contain a high level of β-glucan. The AX from rye, wheat, and triticale and β-glucan from barley and oats are to a large extent soluble, whereas the solubility of AX found in corn and sorghum is lower than the other cereals. The ratio of arabinose to xylose gives a crude indication of the AX structure, which varies between the endosperm, the aleurone and the outer grain layers as well as between the same tissues from different grains. Varietal differences in AX structure of the endosperm are also identified. From the analysis of the released oligomers after hydrolysis with a specific (1→3,1→4)-β-d-glucan hydrolase, it is found that the ratio of trisaccharides (degree of polymerization 3) and tetrasaccharides (degree of polymerization 4) varies depending on the source, being higher in barley than in oats but lower than in wheat. The molecular weight of β-glucan is higher than that of AX, and both polymers contribute to the viscosity of the extract. However, because AX molecules are more resistant to degradation than β-glucan, the use of AX rich grains in broiler diets is usually more problematic than those containing high concentrations of β-glucan. The cereal coproducts (brans and hulls) are concentrated sources of cellulose, lignin, and insoluble AX, but β-glucan can also be present mainly in rye and wheat brans. The CW composition of seeds and grains of protein crops and feedstuffs are different from that of cereals. The main CW polymers are pectic substances (homogalacturonan, rhamnogalacturonan type I and II, xylogalacturonan, and arabinogalactans type I and II), xyloglucans, and cellulose, but there are significant differences in the composition of the parenchymatous (cotyledon) tissues and that of the hulls. In the hulls, cellulose is the predominant polysaccharide, followed by acidic xylans and pectic substances. The implications of the heterogeneous CW for the action of exogenous enzymes are discussed.

Effects of a mono-component endo-xylanase supplementation on the nutritive value of wheat-based broiler diets

1. Two trials were conducted to evaluate the effects of a mono-component thermostable endo-1,4-β-xylanase derived from Thermomyces lanuginosus on the nutritive value of wheat-based broiler diets. In a 5-week growth trial, the efficacy of xylanase supplementation at 0, 100, 150, 200, 400 and 4000 FXU/kg diet was evaluated. A short-term balance trial was carried out according to a 4 × 2 factorial arrangement of treatments, involving 4 wheat cultivars and endo-xylanase at 0 or 200 FXU/kg. 2. In the growth trial, enzyme supplementation from 0 to 400 FXU/kg reduced feed intake and improved feed conversion linearly. Digesta viscosity was significantly reduced by all enzyme inclusion levels by 49·6-56·9%, in a quadratic manner. 3. In the balance trial, xylanase supplementation resulted in a significant improvement of protein, lipid and dry matter apparent digestibility coefficients of diets, accompanied by improved dietary AME(N) values. There was a significant wheat × enzyme interaction on AME(N) and lipid digestibility. There was a significant effect of wheat cultivar on dry matter digestibility.

Metabolizable energy and digestible amino acid prediction of wheat using mathematical models

Wheat is a common raw material used to provide most of the energy and a great portion of amino acids in poultry diets. The routine investigation of metabolizable energy (ME) and digestible amino acid content determination are costly and time consuming for wheat grains. Therefore, it would be helpful if the energy and digestible amino acid content of wheat grain samples could be predicted from their chemical composition. Three studies were conducted to evaluate the probability of AMEn, AME, and apparent ileal digestible amino acid (AIDAA) prediction in wheat samples based on chemical compositions. Multiple linear regression (MLR), partial least square (PLS), and Artificial neural network (ANN) methods were developed to estimate the AME values of wheat grain samples based on total and soluble nonstarch polysaccharides (study 1) and the AMEn based on DM, CP, and ash (study 2). Furthermore, MLR and ANN models were used to estimate the AIDAA via CP content of wheat samples (study 3). The fitness of the models in each study was tested using R2 values, RMS error, mean absolute deviation, mean absolute percentage error, and bias parameters. The results of studies 1 and 2 showed that AME can be predicted from the chemical composition. The prediction of AME of wheat through the ANN-based model showed higher accuracy and lower error parameters as compared with MLR and PLS models in both studies (1 and 2). The results of the third study indicated that CP can be used as a single model input to predict AIDAA in wheat samples. Furthermore, the ANN model may be used to improve model performance to estimate AIDAA as affected by CP content. The results demonstrated that the ANN model may be used to accurately estimate the ME and AIDAA values of wheat grain from its corresponding chemical compositions. As a result, this method provides an opportunity to reduce the risk of an unbalanced level of energy and amino acid in feed formulation for poultry.

Review: Prediction of variation in energetic value of wheat for poultry

Yegani, M. and Korver, D. R. 2012. Review: Prediction of variation in energetic value of wheat for poultry. Can. J. Anim. Sci. 92: 261–273. Variations in physical and chemical characteristics of wheat can significantly influence the energy availability of this feed ingredient for poultry. These variations can result in inefficiencies in the form of over- or under-formulation of the diets at commercial feed mills or on poultry farms. Therefore, having a clear understanding of the variations is of paramount importance in the formulation of poultry diets as they can have negative consequences for production performance of birds. There are a large number of factors that can contribute to variations in energy availability of wheat for poultry. This review is intended to briefly discuss these factors and also practical approaches that can be used to predict these variations. These approaches include measuring physico-chemical characteristics, in vivo digestibility trials, in vitro digestibility techniques, and near infrared reflectance spectroscopy (NIRS). There are limitations associated with physico-chemical and in vivo measurements. However, in vitro digestibility techniques are simple and fast and can provide data for database development and ongoing calibrations of NIRS systems. Near infrared reflectance spectroscopy has enormous potential to predict variations in wheat apparent metabolizable energy, leading to more accurate diet formulation.

Improving the efficiency of feed utilization in poultry by selection. 1. Genetic parameters of anatomy of the gastro-intestinal tract and digestive efficiency

Background

Feed costs represent about 70% of the costs of raising broilers. The main way to decrease these costs is to improve feed efficiency by modification of diet formulation, but one other possibility would be to use genetic selection. Understanding the genetic architecture of the gastro-intestinal tract (GIT) and the impact of the selection criterion on the GIT would be of particular interest. We therefore studied the genetic parameters of AMEn (Apparent metabolisable energy corrected for zero nitrogen balance), feed efficiency, and GIT traits in chickens.

Genetic parameters were estimated for 630 broiler chickens of the eighth generation of a divergent selection experiment on AMEn. Birds were reared until 23 d of age and fed a wheat-based diet. The traits measured were body weight (BW), feed conversion ratio (FCR), AMEn, weights of crop, liver, gizzard and proventriculus, and weight, length and density of the duodenum, jejunum and ileum.

Results

The heritability estimates of BW, FCR and AMEn were moderate. The heritability estimates were higher for the GIT characteristics except for the weights of the proventriculus and liver. Gizzard weight was negatively correlated with density (weight to length ratio) of duodenum, jejunum and ileum. Proventriculus and gizzard weights were more strongly correlated with AMEn than with FCR, which was not the case for intestine weight and density.

Conclusions

GIT traits were largely dependent on genetics and that selecting on AMEn or FCR would modify them. Phenotypic observations carried out in the divergent lines selected on AMEn were consistent with estimated genetic correlations between AMEn and GIT traits.

Wheat starch digestion rate affects broiler performance

Two experiments were conducted to determine the differences in starch digestion rate (KDS) among wheats from different cultivars and origins and to verify if chickens would benefit from a certain digestion rate of starch. In the first experiment, 192 chickens (21 d) were assigned to 4 diets containing 55% of each wheat sample (3 cultivars, one of them from 2 origins). Starch and protein digestion were calculated from the remaining starch and protein in 4 segments of the small intestine and in excreta, using chromic oxide as a marker. Mean retention time was measured in each segment, which enabled calculations of digestion rates. In the second experiment, 2,600 chickens were assigned to 5 isoenergetic and isonitrogenous diets (with KDS from 1.80 to 2.56 h(-1)) and growth performance was determined (1 to 34 d). In 3 treatments, dietary starch was provided each by the wheat cultivars (same origin), whereas in the other 2 treatments, 25 and 50% of the wheat starch with the highest KDS was substituted by pea starch. Clostridium perfringens and Lactobacillus in the cecal chyme and glucose in the blood (glycemic index) were measured in broilers at d 19 and 25, respectively. Starch was gradually digested along the small intestine, mainly in the jejunum (48.5 and 80.4% at proximal and distal jejunum) where the largest differences among wheat samples were found. Starch digestion rate varied with origin (from 1.96 to 2.56 h(-1)) and cultivar (from 2.17 to 2.56 h(-1)). Crude protein digestion rate (average 2.21 h(-1)) was not affected by either cultivar or origin. Broiler growth and feed conversion ratio improved in a quadratic way with KDS. The maximum broiler performance was observed with KDS around 2.2 h(-1). Blood glucose response (glycemic index) was not affected by KDS; therefore, it cannot be used to predict broiler performance. In conclusion, the rate of starch digestion varies among wheats, depending on both genetic and environmental conditions of the grain, and affects broiler performance.

Effect of wheat cultivar and enzyme addition to broiler chicken diets on nutrient digestibility, performance, and apparent metabolizable energy content

A total of 5,000 one-day-old male broiler chickens were assigned to 8 different treatments in a 4 x 2 factorial design. Four wheat cultivars (Amiro, Guadalupe, Isengrain, and Horzal) and 2 levels (0 or 1 kg/t of feed) of an enzyme cocktail (Avizyme 1300, xylanase, 2,500 U/kg and protease, 800 U/kg) were used. Nutritionally complete mash diets contained 65 and 70% of the test wheat for the starter and grower period, respectively. Test wheats were used in diets for broilers, and growth performance and AME contents were measured. Broiler performance was measured in 4,800 broilers allocated to floor pens with 75 birds each and fed from 1 to 42 d of age. Digestibilities and AME contents of diets were measured in 200 broilers from 6 to 27 d of age individually allocated to battery cages. Chromic oxide (Cr(2)O(3)) at an inclusion rate of 0.5% in the diet was used as an indigestible marker. Apparent metabolizable energy was corrected by zero N balance to obtain AME(n). Wheat cultivar strongly influenced animal performance during the starter period (1 to 21 d of age). During the grower period (21 to 42 d of age), only BW and daily feed intake were influenced by wheat cultivar. Differences in daily feed intake were associated with differences in AME(n) intake during the starter period, but not during the grower period. Nutrient digestibility was higher with the use of enzyme. Animal performance was not affected (i.e., wheat cultivar differences were not eliminated by using enzymes). During the grower period, significant interactions were detected with regard to nutrient digestibility and AME(n). Differences in AME(n) content of wheat could not be explained by digestible starch.

Effect of feeding silages or carrots as supplements to laying hens on production performance, nutrient digestibility, gut structure, gut microflora and feather pecking behaviour

1. An experiment was carried out to examine the suitability of using maize silage, barley-pea silage and carrots as foraging materials for egg-laying hens. Production performance, nutrient digestibility, gastrointestinal characteristics, including the composition of the intestinal microflora as well as feather pecking behaviour were the outcome variables. 2. The protein content of the foraging material (g/kg DM) was on average 69 g in carrots, 94 g in maize silage and 125 g in barley-pea silage. The starch content was highest in the maize silage (312 g/kg DM), and the content of non-starch polysaccharides (NSP) varied from 196 to 390 g/kg, being lowest in carrots. Sugars were just traceable in the silages, whereas carrots contained on average 496 g/kg DM. 3. Egg production was highest in hens fed either carrots or maize silage, whereas hens fed barley-pea silage produced less (219 vs. 208). Although the consumption of foraging material was high (33, 35 and 48% of the total feed intake on 'as fed' basis for maize silage, barley-pea silage and carrots, respectively) only a minor effect on nitrogen corrected apparent metabolisable energy (AME(n)) and apparent digestibility was seen. At 53 weeks of age, hens fed maize silage had AME(n) and apparent digestibility values close to the control group (12.61 and 12.82, respectively), whereas access to barley-pea silage and carrots resulted in slightly lower values (12.36 and 12.42, respectively). Mortality was reduced dramatically in the three groups given supplements (0.5 to 2.5%) compared to the control group (15.2%). 4. Hens receiving silage had greater relative gizzard weights than the control or carrot-fed groups. At 53 weeks of age, the gizzard-content pH of hens receiving silage was about 0.7 to 0.9 units lower than that of the control or carrot-fed hens. Hens fed both types of silage had higher concentrations of lactic acid (15.6 vs. 3.2 micromoles/g) and acetic acid (3.6 vs. 6.1 micromoles/g) in the gizzard contents than the other two groups. The dietary supplements had a minor effect on the composition of the intestinal microflora of the hens. 5. Access to all three types of supplements decreased damaging pecking in general (to feathers as well as skin/cloaca), reduced severe feather pecking behaviour and improved the quality of the plumage at 54 weeks of age. 6. In conclusion, access to different types of foraging material such as silages and carrots improved animal welfare.

Effects of wheat quality on digestion differ between the D+ and D- chicken lines selected for divergent digestion capacity

The aim of the experiment was to study the effects of 2 wheat cultivars (Baltimor and Scipion) with different hardness values (75 and 5, respectively) on 2 divergent lines (D+ and D-) of broiler chickens selected on the basis of their digestion ability assessed by AME(n). Wheat was incorporated at 54.6% in diets. The other main ingredients were soybean meal (35.3%) and rapeseed oil (5.5%). Diets were given as pellets from 7 to 26 d. The experimental design was a 2 x 2 factorial design testing 2 wheat cultivars (soft or hard) on 2 selected lines of broiler chickens (high AME(n) or low AME(n)). From 7 to 16 d, D+ line showed lower (P < 0.0001) feed intake and feed:gain ratio than the D- line. At 3 wk of age, the D+ chickens resulted in increased digestibility values (P < 0.01) and 9% increased AME(n) value (P < 0.0001) compared with D-. Wheat cultivar effects on feed efficiency and AME(n) differed between lines. In the D+ line, their values were about 6% higher (P < 0.05) with soft than with hard wheat, whereas they did not differ in the D- line. However, wheat cultivar effect on starch digestibility did not differ between lines; soft instead of hard wheat resulted in about 6% improvement (P < 0.0001) in both lines. In the D- line, soft instead of hard wheat tended to reduce lipid and protein digestibilities, which explained why the starch digestibility improvement due to soft wheat was not converted into a significant AME(n) improvement in D birds. Study of digestive organ size revealed that increased proventriculus and gizzard weight (P < 0.05) could be one of the causes for the better digestion capacity of the D+ line. The pancreas was bigger (P < 0.01) in D- than in D+ birds, which probably came from an adaptation to a digestive disorder in D- birds.

Nutritive values of corn, soybean meal, canola meal, and peas for broiler chickens as affected by a multicarbohydrase preparation of cell wall degrading enzymes

The effect of a new multicarbohydrase supplement of cell wall degrading activities on the nutritive value of corn, soybean meal (SBM), canola meal (CM), and peas for broiler chickens was investigated. Four isoenergetic and isonitrogenous corn (69% corn), SBM (30% SBM, 59% corn), CM (30% CM, 54% corn), and pea (30% peas, 52% corn) diets, without or with enzyme supplementation, were formulated to meet NRC specifications for broiler chickens (except for AME and CP, which were at 95 and 92% of NRC requirements, respectively). The enzyme supplement supplied 1,000 U of xylanase, 400 U of glucanase, 1,000 U of pectinase, 120 U of cellulase, 280 U of mannanase, and 180 U of galactanase per kilogram of diet. Each diet was fed in a mash form to 9 replicate pens of 5 broilers from 5 to 18 d. When compared with the control treatment, enzyme addition to the corn diet improved (P < 0.05) feed-to-gain ratio, whereas the performance of birds fed the other 3 diets was not affected. An increase (P < 0.05) in total tract nonstarch polysaccharides (NSP) digestibility, ileal starch digestibility, and AMEn was observed in birds fed the enzyme-supplemented corn diet. An improvement (P < 0.05) in total tract NSP digestibility, ileal protein digestibility, and AMEn content with enzyme supplementation was observed for the SBM diet. However, nutrient digestibilities and AMEn of CM and pea diets were not affected (P > 0.05) by enzyme addition even though the NSP digestibilities increased significantly (P < 0.05). A significant increase (P < 0.05) in water-soluble NSP and a decrease (P < 0.05) in water-insoluble NSP concentration of ileal digesta was noted for birds fed all 4 enzyme-supplemented diets. It would appear from this study that the nutrient utilization of corn-SBM diet by broilers could be enhanced by using an appropriate multicarbohydrase enzyme supplement. The nutrient encapsulating effect of cell wall polysaccharides in SBM, CM, and peas may not be the only factor responsible for incomplete nutrient utilization. The improvement in feed efficiency and starch availability in birds fed corn diet likely resulted from the cell wall degrading activity of the enzyme supplement.

Degradation of cell wall polysaccharides by combinations of carbohydrase enzymes and their effect on nutrient utilization and broiler chicken performance

In vitro incubation studies were carried out to determine if various carbohydrase preparations contained appropriate activities to target nonstarch polysaccharides (NSP) of wheat, soybean meal (SBM), canola meal, and peas. Triplicate samples (0.1 g) were incubated with a number of carbohydrase preparations (i.e., cellulase, pectinase, xylanase, glucanase, galactanase, and mannanase) or their combinations at 45 degrees C and pH 5.2. A more pronounced degradation of NSP was achieved when the enzyme preparations were used in concert. When compared with the control (nonenzyme treatment), the highest degree of NSP degradation reached was 37% for wheat, and 36, 26, and 28% for canola meal, SBM, and peas, respectively. Four enzyme combinations were studied further in a 2-wk (5 to 18 d of age) growth performance and nutrient digestibility trial with broiler chickens. All enzyme combinations were effective in improving (P < 0.05) weight gain, feed-to-gain ratio, AMEn, apparent ileal digestibilities of starch and protein, and apparent total tract digestibility of NSP in birds fed a wheat, wheat screening, SBM, canola meal, and peas-based diet. The most complex enzyme combination was found to be superior (P < 0.05) to others in improving ileal protein digestibility and feed-to-gain ratio. The effectiveness of this combination in elimination of the nutrient-encapsulating effect of cell walls was further evaluated in a balance study with adult roosters fed a conventionally ground full-fat canola seed. Enzyme addition increased (P < 0.05) NSP digestibility from 11.1 to 30.1%, which, in turn, resulted in a marked increase (P < 0.05) in TMEn value (4.176 vs 4.744 Mcal/kg) of the seed. It is evident from the present studies that the addition of an appropriate combination of carbohydrase enzymes to target cell wall polysaccharide structures could further improve enzyme efficacy in practical wheat, SBM, canola meal, and peas-based broiler diets.

The incorporation of whole grain into pelleted broiler chicken diets. II. Gastrointestinal and digesta characteristics

1. Pelleted diets, incorporating whole or ground wheat or barley in the pellets, were fed to broiler chickens and the performance, gastrointestinal development and digesta characteristics of those chickens recorded. 2. Body weight was similar with whole grain incorporation or enzyme application. Food conversion efficiency was improved by addition of enzyme to a full wheat diet. 3. Whole grain inclusion in pellets reduced proventriculus proportional mass and increased gizzard proportional mass with no apparent effects of exogenous feed enzyme addition. 4. Relative ileal mass was reduced by enzyme inclusion in a wheat diet and by inclusion of whole barley in the pellets. 5. Digesta viscosity was increased by whole wheat inclusion but reduced by enzyme inclusion irrespective of grain processing. Inclusion of 200 g/kg of barley did not alter viscosity of digesta beyond the duodenum. 6. Fresh excreta pH was higher with both cereals in the grower phase when whole grain was fed. On the barley diet, this was affected by enzyme addition, which created higher pH from a point earlier in the grower phase than when no enzyme was employed. 7. Evidence of a complex interaction between higher viscosity and pH being involved in differences in ileal relative mass was found through significant relationships being produced by enzyme use on the wheat diet alone.